CN103632117A - Active RFID (Radio Frequency Identification) positioning method based on direct sequence spread spectrum technology - Google Patents
Active RFID (Radio Frequency Identification) positioning method based on direct sequence spread spectrum technology Download PDFInfo
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- CN103632117A CN103632117A CN201310612126.XA CN201310612126A CN103632117A CN 103632117 A CN103632117 A CN 103632117A CN 201310612126 A CN201310612126 A CN 201310612126A CN 103632117 A CN103632117 A CN 103632117A
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Abstract
The invention discloses an RFID (Radio Frequency Identification) positioning method based on a direct sequence spread spectrum technology. The method mainly comprises the steps: a fixed tag awakes an appointed mobile tag through broadcasting the positioning information; the mobile tag replies the position information by a direct spread spectrum sequence; the distance information is computed by the fixed tag and is transmitted to a reader; a host computer collects a plurality of pieces of distance information from the reader and calculates the position of the mobile tag. The communication between the position tag and the mobile tag is completed by using the direct spread spectrum sequence, and the position of the tag is obtained by calculation; thus when the measurement distance is longer, the measurement precision can be still higher.
Description
Technical field
The invention belongs to wireless communication technology field, relate to a kind of active RFID localization method, specifically a kind of design of the active RFID localization method based on direct sequence spread spectrum skill.
Background technology
The localization methods such as existing radio frequency location short-distance technique has that radar fix, wireless direction-finding walk, signal intensity RSSI location, TOA (radio signal transmission time) and TDAO (radio signal transmission mistiming).Radar is searched positioning system, use exactly radar outwards to transmit in different directions, again by by the analysis of searching target return signal, determine by the position of searching target, the exemplary of this way, utilizes military radar to search enemy's aircraft exactly, but this method is due to apparatus expensive, bulky, be not obviously suitable for general position application yet.The wireless direction-finding system that walks, first need to be with it the object of being searched, a simple wireless signal generating means is installed, intermittently outwards transmit, search personnel need to utilize and move towards antenna and audiomonitor is determined the roughly direction of signal source, and according to the power of signal, judge by the Position Approximate of searching target, although this method is simple, poor accuracy.
Due to the progress of technology, the micropower transceiver that current many single-chips are made, all has signal intensity indication (RSSI) function, thereby, the signal intensity size (RSSI) that utilization receives, differentiates moving target position, also becomes a kind of method of location.
Utilize and measure radiofrequency signal from searching target, to the method for monitoring radio receiver monitor transmission time (TOA) location, due to very high to the synchronous requirement of signal source and signal receiver time, thereby also impracticable; Utilize and measure two kinds of unlike signals (for example radiofrequency signal and ultrasonic signal), the method of location from signal source to signal receiver transmission time difference (TDOA), owing to need to using two kinds of different signals, also just need to use two kinds of equipment that transmit and receive unlike signal, for example ultrasound wave occurs and receiving equipment, this has just strengthened cost, simultaneously, the accuracy of this localization method is directly related with the precision of time difference measurements, this has just increased its use difficulty, and this also just hinders its application.
RFID(Radio Frequency Identification) be a kind of wireless communication technology, can identify specific objective and read and write related data by radio signals, and without setting up machinery between recognition system and specific objective or optics contacts.Wireless signal is by the electromagnetic field of furnishing radio frequency, data is sent out from the label being attached to article, with automatic Identification and these article of tracking.The elect magnetic field that some label sends from recognizer when identification just can obtain energy, does not need battery; Also there is label itself to have power supply, and can initiatively send radiowave (electromagnetic field of furnishing radio frequency).But the shortcoming that RFID localization method in the prior art exists is the interference that is easily subject to signal, and if distantly when moving target is positioned also there is the shortcoming that measuring accuracy is not high.
The following logarithm loss model of the general employing of distance-finding method based on RSSI at present:
in formula, d is the distance between transmitter and receiver; d
0it is reference distance; η is fading channel index; General value 2～4; X
σthat average is gaussian random noise variable zero, meansquaredeviationσ; PL (d
0) be range transmission machine d
0the signal intensity at place; PL (d) is the signal intensity at range transmission machine d place; PL (d
0) can draw by experience, or obtain from hardware specification definition.Equation can be obtained apart from d by signal intensity PL (d) thus.Also have in addition decay factor model, this class model has comprised the variation that building type impact and restraining mass cause.Although these methods are very simple, do not need to increase hardware especially yet, because the error at measurment of RSSI signal intensity is very big, influence factor is also a lot, thereby also non-constant of accuracy, particularly closely all the more so among a small circle.
Summary of the invention
The object of the invention is provides a kind of RFID localization method based on direct sequence spread spectrum skill in order to solve the shortcoming that in prior art, RFID localization method exists.
Technical scheme of the present invention is: the RFID localization method based on direct sequence spread spectrum skill, specifically comprises:
S1, the position of fixed labels is set, and the positional information of fixed labels and id information are sent to host computer by reader, by host computer, stored;
S2, by reader, to fixed labels, send positioning instruction, fixed labels receives positioning instruction;
S3, fixed labels are carried out Direct-Spread with mobile tag and are communicated by letter in coverage area, and mobile tag returns back to fixed labels by the id information of itself by direct spreading sequence;
S4, fixed labels are calculated the distance with mobile tag, and the id information of range information and fixed labels is sent to reader, reader receives the locating information of all fixed labels transmissions and uploads to host computer, by host computer, according to the id information of the fixed labels of storage, is compared and obtains the positional information of mobile tag with the locating information receiving.
Further, described fixed labels and mobile tag be by default all in periodic sleep state, every regular time, can from periodic sleep, come to life to intercept in scope, whether there is positioning instruction.
Further, the process that the locating information that described mobile tag sends to fixed labels will experience in mobile tag is: information coding, the generation of signal format, Direct-Spread modulation, baseband filtering, shaping, quadrature up-conversion, passband filtering, signal amplifies, and finally by antenna, sends to fixed labels.
Further, the phase differential that described fixed labels synchronously obtains between up sequence and descending sequence pseudo-code by essence calculates the distance between fixed labels and mobile tag.
Further, between the communication process of the direct sequence spread spectrum between described fixed labels and mobile tag and calculating fixed labels and mobile tag, the process of distance is: first fixed labels general or positioning instruction carry out framing, then carry out spread spectrum, through quadrature up-conversion, be modulated on carrier wave and by antenna transmission and go out, in the region that spread-spectrum signal covers in fixed labels, broadcast;
Mobile tag is received positioning instruction, after demodulation expands, obtain positioning instruction, pseudo-code generator generates and copies pseudo-code sequence, the up sequence that is synchronized with locking, copy pseudo-code sequence and be modulated to descending carrier as downgoing signal, the mode by above-mentioned same direct sequence spread spectrum sends to corresponding fixed labels;
Fixed labels obtains the locating information that feedback is replied by mobile tag, by comparer, contrast the phase place of this pseudo-code sequence and the initial up pseudo-code sequence sending, calculate the mistiming, deduct fixing time delay, obtain total time delay, calculate the distance between fixed labels and mobile tag.
Further, sequence pseudo-code in spread spectrum process selects m sequence as spread-spectrum pseudo code, the form of signal is comprised of frame head, flag, data segment and CRC check, wherein said frame head is for signal trace, flag is as timing time of arrival sign, the ID that data segment comprises location tags and mobile tag, for the differentiation of different labels, CRC check is for error checking and correction.
The invention has the beneficial effects as follows: the present invention is based on the RFID localization method of direct sequence spread spectrum skill by utilizing the communication between direct spreading sequence completing place label and mobile tag, and the distance between the two of calculating, and relevant range information is calculated and sends to reader, reader sends to computing machine by mutually a plurality of range informations, thereby in computing machine, can realize the location of electronic tag in a peacekeeping hyperspace; Because spreading code information is relevant, in an information code, fill out a complete pseudo-code cycle, so the proper phase of available spreading code is as the bit synchronization signal of information code, the precision of range finding just depends on the precision of receiving end pseudo-code tracing like this, and unambiguous distance is determined by the length of information frame, can be for remote range finding, by the mode of spread spectrum, obtain accurate position, then by calculating label position, so just can solve when measuring distance is far away, still obtain higher measuring accuracy.
Accompanying drawing explanation
Fig. 1 is the FB(flow block) of the RFID localization method of the embodiment of the present invention based on direct sequence spread spectrum skill;
Fig. 2 is localizing environment in the RFID localization method of the embodiment of the present invention based on direct sequence spread spectrum skill;
Fig. 3 is the process that in the RFID localization method of the embodiment of the present invention based on direct sequence spread spectrum skill, locating information experiences in mobile tag;
Fig. 4 is the positioning principle figure between mobile tag and fixed labels in the RFID localization method of the embodiment of the present invention based on direct sequence spread spectrum skill.
Embodiment
Below in conjunction with accompanying drawing and specific embodiment, the invention will be further elaborated.
The FB(flow block) that is illustrated in figure 1 the RFID localization method of the embodiment of the present invention based on direct sequence spread spectrum skill, specifically comprises:
S1, the position of fixed labels is set, and the positional information of fixed labels and id information are sent to host computer by reader, by host computer, stored;
S2, by reader, to fixed labels, send positioning instruction, fixed labels receives positioning instruction;
S3, fixed labels are carried out Direct-Spread with mobile tag and are communicated by letter in coverage area, and mobile tag returns back to fixed labels by the id information of itself by direct spreading sequence;
S4, fixed labels are calculated the distance with mobile tag, and the id information of range information and fixed labels is sent to reader, reader receives the locating information of all fixed labels transmissions and uploads to host computer, by host computer, according to the id information of the fixed labels of storage, is compared and obtains the positional information of mobile tag with the locating information receiving.
For those skilled in the art can understand and implement the present invention, below in conjunction with instantiation, be described in detail, be illustrated in figure 2 localizing environment in the RFID localization method of the embodiment of the present invention based on direct sequence spread spectrum skill:
In technical solution of the present invention, mobile tag is a comparatively simple single-chip signal receiver transmitter, its emissive power can be controlled by the mode of software or hardware, generally battery-powered, with chip, carry, in order to reach the object of power saving, after mobile tag is started working, by default, can enter periodic sleep state, will periodically revive at set intervals to intercept whether have the positioning instruction that comes from fixed labels broadcast.If there is the positioning instruction information from fixed labels, mobile tag will be within a shorter time so, and the relevant information of label is sent to fixed labels after by Direct-Spread.
Structure and the mobile tag of fixed labels are roughly the same, its positional information is all fixed and is stored in host computer with the care mutually of self, and same, it also can carry out periodic sleep, will revive at set intervals to intercept the positioning instruction whether having from reader, once have, in the region covering, by frequency expansion sequence, broadcast positioning instruction, and wait receives the positional information that mobile tag returns, calculate relative distance between the two, finally the range information calculating is sent to reader.
General reader is a signal receiver transmitter being connected with host computer, both can with fixed labels carry out communication also can be directly and mobile tag communicate, when positioning, first reader sends positioning instruction to fixed labels, and accept to send the range information of returning by location tags, receive after range information, more relevant distance is sent to host computer.
Host computer is computing machine in general sense namely, id information and its positional information of each fixed labels stored in the inside, also stored the id information of each mobile tag, be used for identifying different label informations, so accept to collect from reader after the range information sending from different fixed labels at it, can calculate the real time position of mobile tag.
Below the course of work by concrete is described in detail, first by reader, to fixed labels, send positioning instruction, fixed labels is to carry out in periodic sleep before receiving the positioning instruction that reader sends, periodically revive to intercept at set intervals the signal of sending from reader, once receive after the positioning instruction that reader sends, just enter duty, and send specific positioning instruction in overlay area, mobile tag is waken up after receiving and specifically waking instruction up, after specific mobile tag is waken up, to corresponding fixed labels, reply a positional information, between fixed labels and mobile tag, with direct sequence spread spectrum, communicate, fixed labels is calculated both distances according to the phasometer between up sequence and descending sequence pseudo-code, the distance that is about to calculate of existing side by side sends to reader, reader identification is from the range information sending over of different fixed labels, and range information is sent to host computer, host computer is according to the fixing positional information of fixed labels and corresponding range information, the real-time position that calculates mobile tag.
Between the communication process of the direct sequence spread spectrum between described fixed labels and mobile tag and calculating fixed labels and mobile tag, the process of distance is: first fixed labels general or positioning instruction carry out framing, then carry out spread spectrum, through quadrature up-conversion, be modulated on carrier wave and by antenna transmission and go out, in the region that spread-spectrum signal covers in fixed labels, broadcast; Mobile tag is received positioning instruction, after demodulation expands, obtain positioning instruction, pseudo-code generator generates and copies pseudo-code sequence, the up sequence that is synchronized with locking, copy pseudo-code sequence and be modulated to descending carrier as downgoing signal, the mode by above-mentioned same direct sequence spread spectrum sends to corresponding fixed labels; Fixed labels obtains the locating information that feedback is replied by mobile tag, by comparer, contrast the phase place of this pseudo-code sequence and the initial up pseudo-code sequence sending, calculate the mistiming, deduct fixing time delay, obtain total time delay, calculate the distance between fixed labels and mobile tag.And the pseudo-code of sequence in spread spectrum process selects m sequence as spread-spectrum pseudo code, the form of signal is comprised of frame head, flag, data segment and CRC check, wherein said frame head is for signal trace, flag is as timing time of arrival sign, the ID that data segment comprises location tags and mobile tag, for the differentiation of different labels, CRC check is for error checking and correction.
At mobile tag, to fixed labels, send in the process of positional information, positional information will be passed through and is roughly: information coding, the generation of signal format, Direct-Spread modulation, baseband filtering, shaping, quadrature up-conversion, passband filtering, signal amplifies, finally by antenna, send to fixed labels, its process as shown in Figure 3.
In the process of obtaining at spread-spectrum signal, because can not surpass a chip in the embodiment of the distance between fixed labels in the present invention and mobile tag in pseudo-code, so do not need to catch this link in carrying out synchronizing process, do not guarantee that phase place is less than the width of a code element, only need to carry out essence and synchronously obtain the phase differential between uplink and downlink pseudo-code, essence is synchronously namely followed the tracks of.The problem of following the tracks of can be solved well by delay lock loop, and final phase differential draws through the pseudo-code phase comparer of location tags, and then can obtain the distance between mobile tag and location tags, its detailed process as shown in Figure 4.
Those of ordinary skill in the art will appreciate that, embodiment described here is in order to help reader understanding's principle of the present invention, should be understood to that the protection domain of invention is not limited to such special statement and embodiment.Everyly according to foregoing description, make various possible being equal to and replace or change, be all considered to belong to the protection domain of claim of the present invention.
Claims (6)
1. the RFID localization method based on direct sequence spread spectrum skill, is characterized in that, specifically comprises:
S1, the position of fixed labels is set, and the positional information of fixed labels and id information are sent to host computer by reader, by host computer, stored;
S2, by reader, to fixed labels, send positioning instruction, fixed labels receives positioning instruction;
S3, fixed labels are carried out Direct-Spread with mobile tag and are communicated by letter in coverage area, and mobile tag returns back to fixed labels by the id information of itself by direct spreading sequence;
S4, fixed labels are calculated the distance with mobile tag, and the id information of range information and fixed labels is sent to reader, reader receives the locating information of all fixed labels transmissions and uploads to host computer, by host computer, according to the id information of the fixed labels of storage, is compared and obtains the positional information of mobile tag with the locating information receiving.
2. the method for claim 1, is characterized in that, described fixed labels and mobile tag be by default all in periodic sleep state, every regular time, can from periodic sleep, come to life to intercept in scope, whether there is positioning instruction.
3. the method for claim 1, it is characterized in that, the process that the locating information that described mobile tag sends to fixed labels will experience in mobile tag is: information coding, the generation of signal format, Direct-Spread modulation, baseband filtering, shaping, quadrature up-conversion, passband filtering, signal amplifies, and finally by antenna, sends to fixed labels.
4. the method for claim 1, is characterized in that, the phase differential that described fixed labels synchronously obtains between up sequence and descending sequence pseudo-code by essence calculates the distance between fixed labels and mobile tag.
5. method as claimed in claim 4, it is characterized in that, between the communication process of the direct sequence spread spectrum between described fixed labels and mobile tag and calculating fixed labels and mobile tag, the process of distance is: first fixed labels general or positioning instruction carry out framing, then carry out spread spectrum, through positive up-conversion, be modulated on carrier wave and by antenna transmission and go out, in the region that spread-spectrum signal covers in fixed labels, broadcast;
Mobile tag is received positioning instruction, after demodulation expands, obtain positioning instruction, pseudo-code generator generates and copies pseudo-code sequence, the up sequence that is synchronized with locking, copy pseudo-code sequence and be modulated to descending carrier as downgoing signal, the mode by above-mentioned same direct sequence spread spectrum sends to corresponding fixed labels;
Fixed labels obtains the locating information that feedback is replied by mobile tag, by comparer, contrast the phase place of this pseudo-code sequence and the initial up pseudo-code sequence sending, calculate the mistiming, deduct fixing time delay, obtain total time delay, calculate the distance between fixed labels and mobile tag.
6. method as claimed in claim 5, it is characterized in that, sequence pseudo-code in spread spectrum process selects m sequence as spread-spectrum pseudo code, the form of signal is comprised of frame head, flag, data segment and CRC check, wherein said frame head is for signal trace, and flag is as timing time of arrival sign, the ID that data segment comprises location tags and mobile tag, for the differentiation of different labels, CRC check is for error checking and correction.
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| CN110321742A (en) * | 2018-03-30 | 2019-10-11 | 华为技术有限公司 | A kind of method and detection device detecting electronic tag |
| CN110677209A (en) * | 2018-07-02 | 2020-01-10 | 刘礼白 | Clock extraction method for code division radio frequency identification passive tag response data |
| CN110907890A (en) * | 2018-11-20 | 2020-03-24 | 电子科技大学 | RFID intelligent goods shelf misplacement detection method |
| CN111771401A (en) * | 2018-02-28 | 2020-10-13 | 三菱电机株式会社 | Wireless terminal, management system, dormancy judgment method and processing method |
| CN114553369A (en) * | 2022-01-10 | 2022-05-27 | 合肥埃科光电科技股份有限公司 | System and method for detecting performance of digital signal cable based on FPGA |
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| CN106469319A (en) * | 2015-08-14 | 2017-03-01 | 阜阳师范学院 | A kind of being based on positions and the visual intelligent monitoring system of motion rail trace |
| CN108108028A (en) * | 2016-11-24 | 2018-06-01 | 华大半导体有限公司 | Utilize the method for ultra-high frequency RFID label control application program |
| CN108108028B (en) * | 2016-11-24 | 2021-02-09 | 华大恒芯科技有限公司 | Method for controlling application program by using ultrahigh frequency RFID (radio frequency identification) tag |
| CN111771401A (en) * | 2018-02-28 | 2020-10-13 | 三菱电机株式会社 | Wireless terminal, management system, dormancy judgment method and processing method |
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| CN110321742A (en) * | 2018-03-30 | 2019-10-11 | 华为技术有限公司 | A kind of method and detection device detecting electronic tag |
| CN110677209A (en) * | 2018-07-02 | 2020-01-10 | 刘礼白 | Clock extraction method for code division radio frequency identification passive tag response data |
| CN110907890A (en) * | 2018-11-20 | 2020-03-24 | 电子科技大学 | RFID intelligent goods shelf misplacement detection method |
| CN114553369A (en) * | 2022-01-10 | 2022-05-27 | 合肥埃科光电科技股份有限公司 | System and method for detecting performance of digital signal cable based on FPGA |
| CN114553369B (en) * | 2022-01-10 | 2023-11-03 | 合肥埃科光电科技股份有限公司 | System and method for detecting digital signal cable performance based on FPGA |
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